Surface treatment technology of aluminum products

With the development of aluminum smelting and machining technology, aluminum products are now widely used in aviation, building materials, vehicles and other sectors. In recent decades, the surface treatment technology of aluminum cnc parts products has developed extremely rapidly. And through frequent scientific and technological exchanges at home and abroad, as well as the efforts of scientific research scholars, some new processes and technologies have been tested and adopted. In general, the surface treatment technology of aluminum products in my country is still in a development period to be developed.

1. Surface treatment before oxidation

The influence of aluminum material composition and purity on the quality of aluminum oxide film has long been known to scientific and technological workers. In industrial production, the surface machining quality of domestic aluminum products seriously affects the quality of anodized products, and this contradiction is becoming more and more prominent. All foreign aluminum products have been milled, smooth as a mirror, and excellent in quality after oxidation. In our country, aluminum materials often have low gloss, air bubbles, scratches, and heavy skin roughness. These defects are still exposed after anodizing. Therefore, improving the appearance quality of the sheet becomes an important part of ensuring the best quality of oxidation of aluminum products.

2. Oxidation process

Sulfuric acid method, oxalic acid method, chromic acid method oxidation process, especially sulfuric acid anodizing method, almost everyone who is engaged in surface treatment of aluminum cnc parts products knows. These oxidation methods have their own characteristics and application ranges. For example, the oxalic acid method can obtain a thicker oxide film layer. The oxide film itself has some decorative colors, but this method has high cost and high power consumption. The sulfuric acid process oxide film is transparent and colorless, has good color absorption performance, and the electrolyte composition is simple and stable, the process operation is easy, and the cost is low, so it is widely used. However, the temperature control range of the sulfuric acid method is small and the temperature rises quickly. It is often necessary to install refrigeration equipment, which becomes another difficulty.

3. Finishing after oxidation

After oxidation, many aluminum products have to be dyed or printed and sprayed to obtain a variety of bright colors or beautiful patterns and increase fancy varieties. In 1980, it passed the transfer printing method for aluminum products appraised by the Ministry of Light Industry, which can obtain various color patterns with clear patterns, bright colors and full layers. The transfer printing method of aluminum products is also called sublimation transfer color process. Its basic principle is to use disperse dyes to specially make transfer inks, which are printed on paper according to the pattern requirements to make color printing paper, and then the printing paper is attached to the aluminum product. On the oxide film, by heating and pressing, the disperse dyes on the printing paper are transferred into the oxide film micropores in the gas phase to form a colorful pattern. The transfer printing method, with its technology beyond the traditional oxidation dyeing method, can obtain color images on the surface of aluminum products, thus attracting many aluminum products manufacturers to pay attention to testing and production. At this stage, the cost of the process is still high, and the manufacturing of transfer printing paper must rely on the printing industry, and most of the high-temperature pressurized transfer of color patterns is still in the manual operation stage. Theoretically, the mechanism of printing transfer seems to have not been thoroughly discussed. Many people believe that the disperse dye in the ink is transferred to the oxide film layer under high temperature heating conditions. However, some test results show that the thickness and adsorption performance of the oxide film layer also play a very important role, so it will not be a simple sublimation phenomenon of disperse dyes. It is believed that with the continuous exploration of the transfer mechanism, the continuous improvement of the application process and the accumulation of experience, the transfer printing method will open up a broad new field for the beautification and decoration of aluminum products.

4. Other surface treatment processes

In addition to oxidation dyeing, aluminum products also have some other surface treatment processes, such as painting or spray painting. The spray painting process is to spray the amino baking paint on the aluminum products after degreasing and whitening, and then air them. For spray painting, nitro-colored spray paint is used. First, the primer is sprayed, then the pattern is sprayed, and finally the varnish is sprayed. Painting and spray painting techniques are widely used in the production of aluminum buckets, spittoons, basins, tea trays and other products in aluminum products factories in Jiangsu and other provinces.

In recent years, many new aluminum cnc parts surface treatment technologies have been developed abroad, such as electrolytic coloring, polytetrafluoroethylene coating and enamel technology, etc., and have been used in industrial production to make the surface of aluminum products more colorful and suitable for various purposes. Some domestic scientific research units and factories have also experimented with these processes, and it is believed that a large number of such products will be seen in the domestic market soon.